The fuel ethanol fermentation is challenged by microbes that compromise yeast fermentation. Certain common bacterial immunogens of Lactobacillus and similar bacteria can contaminate fermentation flasks for things like alcohol production. These include but are not limited to Lactobacillus spp. Jespersen and Jakobsen, Int. J. Food Microbiology 33:139-155, 1996 review specific groups of gram positive bacteria that are generally considered hazardous beer spoilage organisms in modern breweries. This group of lactobacilli are considered the primary problem. Detection of specific organisms is not always easy with cultivation in laboratory media.
These microbes consume energy that would otherwise be available for the yeast and excrete materials that can inhibit the yeast fermentation. The Lactobacillus spp. often take a measurable toll on the productivity of fuel ethanol plants. For this reason, ethanol producers expend significant resources attempting to minimize these contaminates. Different strains of microbes can have different impacts on the type of fermentation. Hynes, et. al, J. Ind. Micro. and Biotech. 18:284-291, 1997 lists the following: L. rhamnosus, from corn steep liquor, L. rhamnosus, from fermented beets, L. delbrueckii, from sour grain mash, and L. paracasei and L. plantarum, from Brazilian industrial ethanol plant. Brewing, mashes, fermented foods may have problems with different strains from the ethanol plants. Hynes et al, tested the use of virginiamycin to control lactic acid bacteria using alcohol fermentation. They found that different strains of Lactobacillus had different levels of resistance to the antibiotic. It was clear using yeast and wheat mash that the level of virginiamycin would have to be monitored depending on the strain.
If there were a new product that could selectively kill or immobilize these problem species there would be a demand for the product. The bulk of ethanol production is currently manufactured via continuous fermentation, not batch and this continuous process requires constant management of contamination levels. It is likely that antibiotics are currently used for periodic adjustment of contamination levels in continuous processes. Newer plants tend to run with little to no antimicrobial additives. Clearly, there is a need to find newer ways to control these microbes in the fermentation process.
Lactobacillus spp. produce enzymes that contaminate fermentation processes. Bayrock and Ingledew, J. Ind. Microb. and Biotech. 27:39-45, 2001 report on the changes in steady state of a multistage continuous ethanol fermentation system when Lactobacillus of various species were added to a continuous culture for ethanol fermentation. They showed that different species of Lactobacillus were able to grow or be supported under the different conditions in the fermentor. They estimate that between 2% and 11% of ethanol yield is lost if the batch fermentation is contaminated with Lactobacillus. They did find that due to the unique media conditions, L. paracasei growth is supported only in the first fermentor stage of the multistage unit.
Chang, Kim and Shin, Applied and Environmental Microbiology, 63(1): 1-6, 1997 analyzed an industrial-scale ethanol fermentation process and isolated lactic acid bacteria from the process. They wanted to evaluate sulfite as a control agent in a cell-recycled continuous ethanol fermentation process. They found differences between the effect of sulfite on L. casei and L. fermentum. They conclude that sulfite could be used with no harm to the yeast to treat cell-recycled continuous ethanol fermentation processes.
Narendranath et. al., Applied and Environmental Microbiology, 63(11): 4158-4163, 1997 studied the effects of lactobacilli on yeast-catalyzed ethanol fermentation. They determined the production of lactic acid and the suspected competition with yeast cells were the major reasons for the reduction in yeast growth and final ethanol yield.
In many fermentation operations, the challenge is not the yeasts but relates to microbial growth rates and shifts in bacterial populations, and significantly influences the systemic metabolic state. De Oliva-Neto and Yokoya, World J. Microbiology and Biotechnology, 10: 697-699, 1994 evaluated the effect of bacterial contamination on a fed-batch alcoholic fermentation process. They showed that L. fermentum will strongly inhibit commercial baker's yeast in a batch-fed process. When the total acid exceeded 4.8 g/l it interfered with yeast bud formation and viability with 6 g/l decrease in alcoholic efficiency. They demonstrated the clear need for bacterial control in alcohol fermentation.
Simpson and Fernandez, Letters in Applied Microbiology, 14:13-16, 1992 demonstrated that there was a significant difference between lactic acid bacteria species and their resistance to hop-derived constituents of beer. Frequently, microorganisms isolated on growth media die when re-inoculated into beer. Beer-grown microorganisms tend to flourish when transferred from one beer to another. This becomes a major problem in the brewery industry for the microbiologist who is unable to separate the beer-spoilage lactic acid bacteria from the non-spoilage strains.
Jespersen and Jakobsen, Int. J. Food Microbiology, 33:139-155, 1996 review specific groups of gram positive bacteria that are generally considered hazardous to beer spoilage organisms in modern breweries. This group of Lactobacillus are considered the primary problem. Detection of specific organisms is not always easy with cultivation in laboratory media.
Thomas et. al., J. Applied Microbiology, 90:819-826, 2001 reported on the use of a large yeast inoculum in corn mashes to inhibit lactobacilli contamination during fermentation. This self regulating cascade system allowed for recovery of the yeast and had an insignificant effect on fermentation rate or ethanol yield. If however there were large numbers of the lactobacilli present in the incoming mash or in transfer lines, yeast growth and fermentation rates could be adversely affected. When lactobacilli was pre-cultured in the mash, yeast growth was inhibited and the production of ethanol was reduced by as much as 22%.
Chin and Ingeledew, Enzyme Microb. Technol. 16:311-317, 1994 studied the effect of lactic acid bacteria on wheat mash fermentation prepared with laboratory backset. Lactic acid bacteria are known to be most troublesome group of contaminating bacteria found in breweries, distilleries, and fuel alcohol plants. These bacteria are highly heat-resistant and can metabolize and multiply under low pH and anaerobic conditions. Backsetting is common in most fuel (25 to 75%) ethanol production plants. This can lead to a number of problems due to bacterial contaminants. This may lead to inhibition of ethanol production.
Kleynmans, et. al., System Appl. Microbiol., 11:267-271, 1989 isolated and identified a new strain of Lactobacillus from apple and pear mashes. The strain is called L. suebicus. The type strain is strain DSM. These fruit mashes can include fruit brandies and fruit mashes that are fermented and distilled.
A principal objective of the present invention is to substantially prevent the colonization of deleterious organisms such as Lactobacillus spp., as well as the growth of such organisms resulting in their substantial elimination from the system by the administration of fowl egg antibody to the specific organisms.
Haptens are partial or incomplete immunogens such as certain toxins, which cannot by themselves cause antibody formation but are capable of combining with specific antibodies. Such haptens may include bacterial toxin, yeast mold toxin, viruses, parasite toxins, algae toxins, etc.
Under the most popular fermentation systems, the problem with carry over and development of resistant strains of microorganisms are also of major concern to the industry. The use of broad-spectrum antibiotics has further drawbacks including vulnerability to human error, additional cost, consumer resistance, and the like. In addition, most antibiotic additives cannot be added with the commonly used media-based supplements. Avall-Jaskelainen et al., Applied and Environmental Microbiology, 68(12): 5943-5951, 2002 teaches that the Lactobacillus brevis has a number of S-layer epitopes that can be used to make antigens. They were able to construct model epitopes from L. brevis that were heterologous as part of the outermost proteinacous S-layer of the cell. It is proposed but not shown that they could immunize animals with these epitopes.
Narendranath et. al., Applied and Environmental Microbiology, 66(10): 4187-4192, 2000 were able to test the use of urea hydrogen peroxide in ethanol fermentation to control lactobacilli. They showed that it nourishes yeast and leaves no residues in the product. This was tested against five strains of Lactobacillus spp., i.e., L. plantarum, L. paracasei, L. sp. Strain 3, L. rhamnosus and L. fermentum. At a concentration of 32 mmol/liter it only serves as a disinfectant.
Narendranath, Alcohol Times, pages 1 and 3, September 2003 demonstrated from his research that some antimicrobials do not control Lactobacillus at all stages of the life cycle. Lactoside is a product designed to work at all stages as a broad spectrum control. It is currently the only product available. He developed a test for analyzing mash for contamination control. He estimates that 10 million or more cells of Lactobacillus per ml of mash is equivalent to a loss of alcohol yield of 1% or 400,000 gallons for 40 million gallons of alcohol. The main problem with these products are that resistance can occur. These infections rob the ethanol industry of millions of dollar each year.